Thermal detection of single e-h pairs in a biased silicon crystal detector

TL;DR

This study demonstrates the ability to detect and resolve individual electron-hole pairs in a silicon crystal at millikelvin temperatures using advanced phonon sensors, enabling precise charge measurement.

Contribution

The paper introduces a novel silicon detector setup capable of resolving single electron-hole pairs with high precision at very low temperatures.

Findings

Successful detection of single e-h pairs in silicon at 35 mK

Charge quantization observed for both electrons and holes

High-resolution phonon sensor achieved with 0.09 e-h pair noise

Abstract

We demonstrate that individual electron-hole pairs are resolved in a 1 cm$^2$ by 4 mm thick silicon crystal (0.93 g) operated at $\sim$35 mK. One side of the detector is patterned with two quasiparticle-trap-assisted electro-thermal-feedback transition edge sensor (QET) arrays held near ground potential. The other side contains a bias grid with 20\% coverage. Bias potentials up to $\pm$ 160 V were used in the work reported here. A fiber optic provides 650~nm (1.9 eV) photons that each produce an electron-hole ($e^{-} h^{+}$) pair in the crystal near the grid. The energy of the drifting charges is measured with a phonon sensor noise $\sigma$ $\sim$0.09 $e^{-} h^{+}$ pair. The observed charge quantization is nearly identical for $h^+$'s or $e^-$'s transported across the crystal.